Unit for retrofitting a light on a dental handpiece, and dental handpiece having such a unit

Abstract

The invention relates to a unit (30, 30') for retrofitting a light on a dental handpiece (1) whose housing (4) terminates at one end with a detachable protective cap (8), wherein a driven shaft (17) is mounted rotatably inside the housing (4), extends into the region of the protective cap (8) and drives a working tool (2), comprising a cap (31), in particular a dust protection cap, which extends along an axis (12) and has attachment means for fastening to the dental handpiece (1), a device (39) arranged inside the cap (31) and serving to generate electrical energy with a stator (43) and a rotor (44), and illuminating means (40), in particular light-emitting diodes (LEDs), wherein the stator (43) has at least one electrical coil (45), of which the windings (46) are arranged on the inner circumference of the cap (31) and are electrically connected to the illuminating means (40), and wherein the rotor (44) has a permanent magnet (49) which can be arranged and driven in rotation inside the cap (31) about the axis (12) and is at a clear radial distance from and axially overlaps the at least one coil (45). The invention further relates to a dental handpiece (1) having such a unit (30, 30').

Description

[0001] Description

[0002] Title of the invention

[0003] Unit for retrofitting a lighting system to a dental handpiece, as well as a dental handpiece with such a unit

[0004] field of technology

[0005] The invention relates to a unit for retrofitting a lighting system on a dental handpiece having the features of claim 1 and to a dental handpiece having such a unit having the features of claim 16.

[0006] State of the art

[0007] In the field of dentistry or dental technology, handpieces are used to carry out extremely precise and delicate work on teeth, dentures and the like, whereby the contour, surface or geometry of the tooth or denture is shaped using a rotary-driven cutting, grinding, milling, drilling or polishing tool.

[0008] The delicate nature of the processing requires optimal illumination of the work area. For this purpose, a workstation is generally equipped with lights that are permanently installed on the periphery of the work site and whose light is directed onto the tooth or denture with the help of a reflector. However, a problem with this is that shadows are cast if the operator of the handpiece or contra-angle handpiece places their body between the light source and the tooth or denture. To prevent this, handpieces or contra-angle handpieces are used that have integrated lighting. By arranging the lighting close to the rotating tool, their light hits the tooth or denture directly and unobstructed. The optimal illumination enables the best possible and high-quality processing.

[0009] Many handpieces in use today lack integrated lighting. If users of such handpieces want to benefit from improved lighting, they would have to replace their old tools with new handpieces. In terms of economic and sustainable operation, this is hardly justifiable, at least for fully functional handpieces.

[0010] Summary of the invention

[0011] Against this background, the object of the invention is to achieve improved illumination of the tooth or denture when working with handpieces, in particular with handpieces without their own light source.

[0012] This object is achieved by a unit for retrofitting a lighting system to a dental handpiece having the features of claim 1 and by a handpiece having the features of claim 16.

[0013] Advantageous further training results from the subclaims.

[0014] The invention is based on the idea of ​​retrofitting existing handpieces that have no or inadequate integrated lighting with a powerful lighting system. Improved illumination in the area of ​​the tool enables the handpiece user to perform work on teeth, dentures, and the like more precisely, thus improving the quality of the work and achieving better results.

[0015] A particularly advantageous feature is that, thanks to the invention, no new handpiece is required to obtain a powerful lighting system. Instead, existing handpieces in a practice can be enhanced with the functionality of powerful lighting. This makes the invention both cost-effective and sustainable.

[0016] Due to the special design and easy handling of a unit according to the invention, retrofitting a handpiece can be carried out quickly and by the user himself without major additional costs, which further increases the cost-effectiveness of the invention.

[0017] According to an advantageous embodiment of the invention, the permanent magnet consists of a neodymium-iron-boron alloy. Such permanent magnets are characterized by a high magnetic field strength even with small dimensions, thus allowing a compact design of the unit according to the invention in the smallest of spaces.

[0018] Accordingly, the arrangement of a soft magnetic material such as ferrite, nickel-zinc or manganese-zinc in the area of ​​the coils proves to be advantageous in order to improve the inductance of the coils and thus enable a reduction in the coil size.

[0019] Preferably, the permanent magnet is circular in shape, which allows for easy sliding of the permanent magnet onto the drive shaft of the handpiece while simultaneously concentrating the mass as close as possible to the rotational axis. This counteracts any imbalance of the permanent magnet.

[0020] The permanent magnet can have a casing on its outside and in particular on its outer circumference, for example made of plastic, which absorbs the centrifugal forces at high speeds of the tool partly as ring tensile forces.

[0021] In a simple embodiment of the invention, the inner circumference of the permanent magnet is matched to the outer circumference of the drive shaft in such a way that a snug fit is achieved, so that both centering and force transmission in the circumferential contact joint between the drive shaft and the permanent magnet are established.

[0022] In an advantageous development of this embodiment, means are arranged in the contact joint between the drive shaft and the permanent magnet to increase the frictional connection. Such means can be surface profiling that leads to micro-toothing of the surfaces, or adhesives or adhesive coatings that create a material-toothed connection.

[0023] A preferred means of increasing the frictional connection is the arrangement of one or more elastic ring elements in one or more circumferential annular grooves on the inner circumference of the permanent magnet's through-bore. The radial contact pressure exerted by an elastic ring element on the drive shaft improves the frictional connection and thus reduces the risk of slippage in the contact joint.

[0024] A further embodiment of the invention provides that the rotor is rotatably mounted on the unit according to the invention and connected to it via the pivot bearings. The unit according to the invention thus has no loose parts, which significantly simplifies its handling and prevents errors during retrofitting. At the same time, any existing imbalances are directly absorbed by the unit according to the invention via the pivot bearings and are not directly transferred to the drive shaft of the handpiece.

[0025] With a view to miniaturizing the design, an advantageous development of the invention provides for the electrical coils to be formed by conductor tracks that are applied, preferably printed, to circuit boards. The circuit boards can be flexible and follow the inner circumference of the cap.

[0026] According to the invention, light-emitting diodes are preferably used as the light source, without, however, excluding other light sources. The light-emitting diodes are preferably arranged on a light source carrier, which simultaneously functions as a circuit board with integrated circuits. The dual function of the light source carrier further promotes a compact design of a unit according to the invention. Without being limited thereto, the invention is explained in more detail below with reference to an exemplary embodiment illustrated in the drawing, wherein further features and advantages of the invention will become apparent. Where possible, identical reference numerals are used for identical or functionally equivalent features of different embodiments.

[0027] Short description of the drawings

[0028] It shows

[0029] Fig. 1 a view of a dental handpiece without integrated lighting,

[0030] Fig. 2 is a longitudinal section through the area marked II in Fig. 1 in the state with retrofitted lighting by means of a first embodiment of a unit according to the invention,

[0031] Fig. 3 a detail of the rotor shown in Fig. 2 in the area of ​​the permanent magnet,

[0032] Fig. 4 shows a cross-section through the handpiece shown in Fig. 2 along the line IV - IV therein,

[0033] Fig. 5 is a cross-section through the handpiece shown in Fig. 2 along the line V - V there, and

[0034] Fig. 6 shows a longitudinal section through the area marked II in Fig. 1 in the state with retrofitted lighting by means of a further embodiment of a unit according to the invention.

[0035] Description of the embodiments

[0036] Fig. 1 shows a view of a known handpiece 1 as used in dentistry for processing teeth, dentures and the like. For this purpose, the handpiece 1 is equipped with a processing tool 2 such as a drill, milling cutter, grinding head or the like, which projects axially beyond the housing 4 of the handpiece 1 at the front end 3 in the area marked II. In its interior, the handpiece 1 accommodates a drive shaft 17 rotating about an axis 5 with a chuck for releasably fastening the processing tool 2, which is described in detail in Figs. 2 to 5. The front end 2 of the handpiece 1 is formed by a protective cap 8, which prevents dust and dirt from entering the clamping area. The protective cap 8 is releasably attached to the housing 4 of the handpiece 1, for example via a thread, so that the clamping area is accessible after removing the cap 8.

[0037] A drive unit 10 with an electric motor and power supply 11 is coupled to the rear end 9 of the handpiece 1. The electric motor directly drives the drive shaft 17, with the rotational axis of the electric motor running coaxially with the drive shaft 17. Also known are embodiments in which the drive unit is arranged separately from the handpiece and both are power-coupled via a flexible shaft.

[0038] The detailed structure of the area marked II in Fig. 1 is shown on a larger scale in Figs. 2 to 5, with the difference that the protective cap 8 according to Fig. 1 is replaced by a unit 30 according to the invention for retrofitting a lighting system.

[0039] Fig. 2 shows the front area II of the housing 4 of the handpiece 1, the longitudinal axis 12 of which coincides with the rotational axis 5. The housing 4 encloses a cavity 13 that is rotationally symmetrical to the axis 12 and in which a work spindle 14 is rotatably mounted in front roller bearings 15 and rear roller bearings 16. The work spindle 14 essentially consists of a drive shaft 17 with a through-bore 18 and with external diameters that vary along its length. In the area of ​​the front end 3, the work spindle 17, with the longitudinal section projecting beyond the front roller bearing 15, forms a collet chuck holder 19 into which an axially displaceable collet 21 is inserted. Towards the end of the collet chuck holder 19, the through-bore 18 of the drive shaft 17 widens to form an internal cone 20.

[0040] The collet 21 consists of a radially slotted sleeve with a slotted clamping cone 22 at the end, which cooperates with the inner cone 20 to clamp the tool. The collet 21 is moved axially relative to the collet chuck 19 via a pulling device 23, whereby the shank of the machining tool 2 is clamped or released due to the corresponding conicities of the inner cone 20 and the clamping cone 22.

[0041] The handpiece 1 shown in Figs. 2 to 5 differs, as stated, from that of Fig. 1 by the replacement of the protective cap 8 with a unit 30 according to the invention for retrofitting a lighting system.

[0042] The unit 30 comprises, among other things, a cap 31 with an approximately hollow-cylindrical longitudinal section 32, which can be connected at its free circumferential edge 33 to the housing 4 of the handpiece 1 coaxially to the axis 5 by means of fastening means. Towards the front end 3, the hollow-cylindrical longitudinal section 32 of the cap 31 is adjoined by an approximately hollow-conical longitudinal section 34 with a central opening 35 for the passage of the machining tool 2.

[0043] In this case, the fastening means consist of an internal thread 36 on the inner circumference of the longitudinal section 32, which interacts with the existing external thread on the housing 4 of the handpiece 1. Additionally, an annular seal 37 is arranged on the opposite outer circumference of the longitudinal section 32, which, together with a connection groove present on the housing 4, ensures a tight connection.

[0044] The interior of the cap 31 accommodates a lighting device 38 and a device 39 for generating electrical energy. The lighting device 38 comprises a plurality of lighting devices 40, such as light-emitting diodes, arranged at uniform circumferential spacing on an annular disk-shaped lighting device carrier 41. In the present embodiment, the lighting device carrier 41 is formed by a circuit board on which, in addition to the light-emitting diodes, the associated electronics are arranged.

[0045] The lamp carrier 41 is fastened coaxially and perpendicularly to the axis of rotation 5 with its outer circumference to the inner circumference of the cap 31, preferably in the region of the hollow conical longitudinal section 34. The lamps 40 are seated on the front annular disc surface and cast their light through axial openings 42 in the cap 31. In order to prevent particles from penetrating into the interior of the cap 31, the openings 42 can be closed with a light-permeable material which is preferably flush with the outside of the cap 31.

[0046] The device 39 for generating electrical energy comprises a stator 43, which interacts with a rotor 44 rotating within the stator 43. The stator 43 consists of several coils 45, each with a plurality of windings 46 made of electrically conductive wire, which are arranged concentrically to the rotation axis 5 on the inner circumference of the hollow cylindrical longitudinal section 32 of the cap 31 and extend approximately over its entire axial length. In this way, the coils 45 define an annular space 47 surrounding the rotation axis 5. To increase the inductance, the coils 45 can additionally have a core made of ferromagnetic material (not shown). The lighting means 40 are supplied with the electrical current generated in the device 39 via electrical lines 48.

[0047] The rotor 44 of the device 39 essentially consists of an annular permanent magnet 49 with a length approximately corresponding to the axial length of the coils 45 or the hollow cylindrical longitudinal section 32. The inner diameter of the central through-opening 50 in the permanent magnet 49 corresponds to the outer diameter of the collet chuck holder 19, so that the permanent magnet 49 can be axially attached to the collet chuck holder 19 with a positive fit. The outer diameter of the permanent magnet 49 is smaller than the annular space 47 enclosed by the coils 45, creating a circumferential air gap 51 with a small radial width.

[0048] The permanent magnet 49 is designed as a dipole diametrically opposed to the rotation axis 5, so that one circumferential half of the permanent magnet 49 represents the magnetic north pole N and the other circumferential half represents the magnetic south pole S (Fig. 4).

[0049] In the embodiment shown in Fig. 2, the permanent magnet 49 is snugly seated on the collet chuck holder 19. The inner circumference of the through-hole 50 is in contact with the outer circumference of the collet chuck holder 19, with the rotational movement being transmitted to the permanent magnet 49 via frictional forces in the contact joint. To improve the force transmission, friction-enhancing means can be arranged in the contact joint between the collet chuck holder 19 and the permanent magnet 49, such as surface profiling and / or adhesive layers applied to one or both contact surfaces.

[0050] An alternative or cumulative measure for this is shown in Fig. 3, which shows the seat of the permanent magnet 49 on the collet holder 19 on a larger scale in longitudinal section. On the inner circumference of the through-hole 50 of the permanent magnet 49, one can see a circumferential annular groove 24 into which a frictional engagement ring 25 is inserted, protruding slightly beyond the inner circumference of the permanent magnet 49. The frictional engagement ring 25 is made of an elastic material such as rubber or silicone, which is radially compressed when the permanent magnet 49 is placed on the collet holder 19, thereby generating a radial contact pressure that improves the frictional connection. This effect can be further enhanced by providing several such frictional engagement rings 25.

[0051] The subject of Fig. 6 is a further embodiment of a unit 30' according to the invention, which largely corresponds to that described in Figs. 1 to 5, so that identical reference numerals are used to the extent of correspondence and, to avoid repetition, reference is made to the explanations therein.

[0052] The special feature of this embodiment is that the rotor 44 is rotatably mounted on the unit 30' and connected to it. For this purpose, the permanent magnet 49, with its through-opening 50, is seated in a rotationally fixed manner on a coaxial bearing bush 26. The outer diameter of the bearing bush 26 essentially corresponds to the inner diameter of the through-opening 50, resulting in a rotationally fixed fit. Alternatively or cumulatively, means can be provided in the joint to increase the frictional connection, for example adhesive means or friction or form-fitting means. Alternatively, the bearing bush 26 and the permanent magnet 50 can also be monolithic, i.e., consist of a single piece. It is also possible for the bearing bush 26 itself to be magnetic.

[0053] The bearing bush 26 has a greater axial length than the permanent magnet 50.

[0054] Due to the central arrangement of the permanent magnet 50 on the bearing bush 26, its ends each form an axial projection beyond the permanent magnet 50. A rotary bearing 27 is arranged on each projection, for example in the form of a roller bearing, whose inner ring 28 is seated rotationally rigidly on the bearing bush 26 and whose outer ring 29 is rigidly connected to the inner circumference of the cap 31. In the present embodiment, the inner circumference of the cap 31 is formed by a ring element 6, into which the coils 45 are integrated, for example by encapsulation.

[0055] To ensure that the unit 30' can be easily attached to the drive shaft 17 and that the rotor 44 can rotate freely in the pivot bearings 27, the inner diameter of the bearing bush 26 is slightly larger than the outer diameter of the drive shaft 17. This creates an annular gap 7 between the bearing bush 26 and the drive shaft 17. To still enable power transmission from the drive shaft 17 to the rotor 44, means 52 for transmitting rotational forces to the bearing bush 26 and thus to the permanent magnet 49 are arranged in the annular gap 7. Suitable means 52 can, for example, be elements that are elastically deformable in the radial direction and which transmit the forces of the rotating drive shaft 17 to the bearing bush 26 and thus to the rotor 44 by means of friction.Such means 52 can be formed, for example, from a felt or a fleece, or consist of a plastic or rubber-like material, which is preferably connected to the inner circumference of the bearing bush 26. The means 52 can completely fill the annular gap 7 or only partially, in the manner of a ring.

[0056] To retrofit lighting on a dental handpiece 1, the existing protective cap 8 is removed in a first step after removing the tool 2, thus gaining access to the freely projecting end section of the drive shaft 17, which in the present embodiment is formed by the collet chuck 19. In a further step, the permanent magnet 49 with its through-opening 50 is then pushed axially onto the drive shaft 17. Due to precisely fitting surface pairings and / or the arrangement of friction-enhancing means in the contact joint, a force-fitting fit of the permanent magnet 49 on the drive shaft 17 results, so that the permanent magnet 49 rotates with the drive shaft 17 during operation of the handpiece 1. Subsequently, the cap 31 according to the invention is attached to the housing 4 of the handpiece 1 in place of the original protective cap 8.In this process, the coils 45 arranged on the inner circumference of the cap 31 assume a position in which they revolve around the permanent magnet 49 while maintaining a small clear radial distance.

[0057] Retrofitting a handpiece 1 with a unit 30' is even easier, since after removing the existing protective cap 8, the unit 30' is simply placed axially onto the drive shaft 17 of the handpiece 1 and connected to the housing 4.

[0058] During operation of the handpiece 1, the permanent magnet 49, which rotates with the drive shaft 17, interacts with the coils 45 to generate electrical current, which is supplied via the electrical lines 48 to the lamps 40 of the illumination device 38. Their light is radiated into the working area of ​​the tool 2 via the openings 42.

[0059] The exemplary embodiment illustrates the invention using a unit for retrofitting lighting on a dental handpiece 1. However, the scope of the invention also includes the retrofitting of other devices according to the invention, such as a Dremel, a hand-held milling machine and the like.

Claims

Claims 1. Unit for retrofitting a lighting unit on a dental handpiece (1), the housing (4) of which is closed at one end by a detachable protective cap (8), wherein a driven shaft (17) is mounted rotatably about an axis (5) within the housing (4), wherein the shaft (17) extends into the area of ​​the protective cap (8) and drives a processing tool (2), comprising - a cap (31) extending along an axis (12), in particular a dust protection cap, with connecting means for attachment to the dental handpiece (1), - a device (39) arranged within the cap (31) for generating electrical energy with a stator (43) and a rotor (44), and - lighting means (40), in particular light-emitting diodes (LED), wherein - the stator (43) has at least one electrical coil (45), the windings (46) of which are arranged on the inner circumference of the cap (31) and which are electrically connected to the lighting means (40), and wherein - the rotor (44) has a permanent magnet (49), - which can be arranged and driven within the cap (31) about the axis (12) and at a clear radial distance and with axial overlap to the at least one coil (45).

2. Unit according to claim 1, characterized in that the permanent magnet (49) has a central through-opening (50) and can be plugged onto the shaft (17) of the handpiece (1) with the through-opening (50) and can be connected to it in a rotationally fixed manner.

3. Unit according to claim 1, characterized in that the permanent magnet (49) has a central through-opening (50) and can be pushed onto the drive shaft (17) of the handpiece (1) with the through-opening (50), wherein the permanent magnet (49) is rotatably mounted on the cap (31) via at least one rotary bearing (27) and means (52) for transmitting rotational forces to the permanent magnet (49) are arranged on the permanent magnet (49).

4. Unit according to claim 3, characterized in that the rotor (44) has a bearing bush (26) onto which the permanent magnet (49) can be plugged with its through-opening (50), wherein the at least one rotary bearing (27) is seated with its inner ring (28) in a rotationally fixed manner on the bearing bush (26) and with its outer ring (29) is connected in a rotationally fixed manner to the cap (31).

5. Unit according to one of claims 1 to 4, characterized in that the permanent magnet (49) is designed as a diametrical dipole.

6. Unit according to one of claims 1 to 5, characterized in that the permanent magnet (49) consists of a neodymium-iron-boron alloy.

7. Unit according to one of claims 1 to 6, characterized in that the permanent magnet (49) is circular in shape.

8. Unit according to one of claims 1 to 7, characterized in that the through-opening (50) of the permanent magnet (49) is adapted to the rotating shaft (17) of the handpiece or angle piece (1) in such a way that the permanent magnet (49) can be arranged with a snug fit on the drive shaft (17) of the handpiece (1).

9. Unit according to one of claims 1 to 8, characterized in that the permanent magnet (49) has means for increasing a frictional connection in the region of the through opening (50).

10. Unit according to claim 9, characterized in that the means are formed by a surface profiling, an adhesive or an adhesive coating.

11. Unit according to one of claims 1 to 10, characterized in that the permanent magnet (49) has a circumferential annular groove (24) in the region of the through opening (50), in which an elastic ring element (25) is arranged.

12. Unit according to one of claims 1 to 11, characterized in that the at least one coil (45) has a ferromagnetic core.

13. Unit according to one of claims 1 to 12, characterized in that the at least one electrical coil (45) is formed by conductor tracks arranged on printed circuit boards.

14. Unit according to one of claims 1 to 13, characterized in that the lighting means (40) are arranged on an annular disc-shaped lighting means carrier (41) which is fastened to the inner circumference of the cap (31).

15. Unit according to claim 14, characterized in that the lighting means (40) are formed by light-emitting diodes and the lighting means carrier (41) by a circuit board on which the light-emitting diodes with integrated circuits are arranged.

16. Dental handpiece with a housing (4) in which a drive shaft (17) rotating about an axis (5) is rotatably held in bearings (15, 16), wherein at the front end of the drive shaft (17) a collet chuck (21) for receiving and driving a tool (2) is arranged coaxially to the axis (5), and wherein the drive shaft (17) or the collet chuck (21) form an axial projection over the front bearing (15), characterized in that - a unit (30) according to one of claims 1 to 15 is arranged in the region of the axial projection of the drive shaft (17) or collet chuck (21), wherein - the permanent magnet (49) is mounted within the cap (31) so as to be rotatable about the axis (5) and is arranged at a clear radial distance and with axial overlap to the at least one coil (45), and - the cap (31) is coaxially attached to the housing (4) by means of detachable connecting means.

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